Yes, Nikki's middle name is mentioned in Blackout and technically it is not canon. I think Nikki's manifestation was promised by quite a few hints in a few different interviews, so it is likely her. Then again,. this is supposed to be a teaser, so I don't mind if it is somebody else.

Well, Joss is quite a specialist in ectopic pregnancies - it's the guy who wrote Alien Resurrection, after all :) And, according to the fairy in Chain "it's not fatal" - so I'd prefer this instead of zompire option.